Multilayer thin-walled bellows are widely used in different branches of engineering, for example in the aircraft building, engine building, and oil industry, when it is necessary to secure the movable jointing of pipelines for compensating their relative displacement.
Stainless steel is the most acceptable material for producing such bellows, because it secures their operation under the conditions of high temperature and pressure, corrosive media and vibration.
A method is known for producing a multilayer thin-walled bellows of stainless steel, including manufacturing round billets by their multiple drawing through matrices using punches with a diameter variation, packing the round billets of given diameter into a multilayer bank, its corrugation into a bellows with subsequent operations of surface deforming and heat treatment--subrecrystallization annealing at a temperature of 680.+-.10.degree. C. (the USSR Inventor's Certificate N.sup.o 1292870, B21D15/00, 1987).
The operation of drawing each billet before packing into the bank allows to increase wall strength, and the heat treatment after the corrugation allows relieving of residual stress in the metal. However, the billet drawing is a rather labour consuming operation. It reduces abruptly the steel ductility and worsens its structure. This fact may cause the appearance of cracks in the bellows during the corrugation, and thus decrease its serviceability under the extreme operating conditions. Besides, the absence of tightness test for external and internal bellows layers after the corrugation may lead to its destruction during the operation.
Another method is known also for producing a multilayer thin-walled bellows of stainless steel, that includes producing thin round billets, rolled up of the sheets and lap or butt welded, their corrugating using a press with a bellows forming and its tightness test by immersing into the water (K. N. Burtsev "Metal Bellows", Mashgiz, 1963, pp. 8-11).
The above described method is less labour consuming as compared with the previous one and allows to keep the chemical composition and the structure of the initial material during the production process. However, the round billet corrugation just after their manufacturing by welding the sheets may cause the formation of cracks both in the welds and in the steel because of their low ductility and strength. Besides, the bellows tightness testing by immersing into the water is more labour consuming and not easily producible.